I am trying to use a library found on the web, called himalaya, which is an html parser.
https://github.com/andrejewski/himalaya
I followed their guide on importing the library, so I do
var himalaya = require('himalaya');
However when I call one of its member functions, I get an error
TypeError: himalaya.parse is not a function
I tried executing himalaya.parse() on the web browser console directly, it works. I tried commenting out the require statement in the js file, the function no longer works on web browser.
I guess this implies the require statement works? But for some reasons I cannot use it in my javascript file, only on the browser console.
Perhaps something with file scopes? Here is part of my code.
var himalaya = require('himalaya');
Template.main.onCreated(function () {
var http = new HttpGet("www.someurl.com/", "/somedirectories/", function (response) {
console.log(himalaya.parse(response.content));
});
http.sendRequest();
});
I am certain that response.content does contain a valid html string.
When you call the himalaya.parse inside the main.onCreated function it seems like the library is not completed loaded at that time. That's why it only runs in your browser console. Check if the himalaya library has a onReady function to let you know exactly when you can use it. If not, you can:
a) Call the parse function inside the main.onRendered or
b) Keep the parse call inside the main.onCreated and set a timeOut to call it after a half second like this:
var himalaya = require('himalaya');
Template.main.onCreated(function () {
var http = new HttpGet("www.someurl.com/", "/somedirectories/", function (response) {
setTimeout(function(){himalaya.parse(response.content)},500);
});
http.sendRequest();
});
If you have an issue with the setTimeout check this answer:
Meteor.setTimeout function doesn't work
Related
This has been bugging me from a long time. I am not well versed with javascript. Here it goes:
How do i store return value of a function into a variable:
lenValue = cy.get(selector).children().length
Above line of code returns undefined But when i try following in cypress test runner console then I get a valid output:
cy.$$(selector).children().length --> gives me correct number
How to return value from inside a then function and catch it to reuse later:
file1.js
function a(selector, attrName){
cy.get(selector).then(function ($el){
return $el.attr(attrName));
}
file2.js
state = file1Obj.a('#name','name')
What you're doing makes complete sense, but simply put, you cannot. (per the docs).
https://docs.cypress.io/guides/core-concepts/variables-and-aliases/#Return-Values
You can, however, use aliases to accomplish what (I think) you're after.
https://docs.cypress.io/guides/core-concepts/variables-and-aliases/#Aliases
#aeischeid shows you the wrong way to do it.
His code works only for a static site, but web pages are rarely static. As soon as API fetches are involved, lucky timing goes out the window and the test bombs.
This is why Cypress commands have automatic retry. Otherwise we could just build tests with jQuery.
Since cy.$$(selector).children().length --> gives me correct number, use that inside the helper function.
function a(selector, attrName) {
return cy.$$(selector).attr(attrName); // jQuery methods used
}
Or
function a(selector, attrName) {
return Cypress.$(selector).attr(attrName); // jQuery methods used
}
But be aware that jQuery only handles static pages, it does not retry if the attribute that you want to query arrives slowly.
For that use a command
cy.get('#name')
.should('have.attr', 'name') // retries until name exists
.then(name => { // guaranteed to have a value
// use name here
})
Here is a example from a cypress test I have that seems pretty relevant
let oldDescription;
cy.get('input#description').should(($input) => {
oldDescription = $input.val();
});
let randomDescription = Math.random().toString(36).substring(7);
cy.get('input#description').clear().type(randomDescription);
cy.get('input#description')
.parents('.ant-table-row')
.contains('Save').click();
cy.get('input#description').should('not.exist');
cy.contains(`${randomDescription}`);
cy.contains(`${oldDescription}`).should('not.exist');
because oldDescription is set inside of an asyncronous callback it isn't safe to expect it to be set, farther down the code outside of that callback, but in a lot of cases with cypress you end up having some other .get call or thing that waits, effectively pausing the code long enough that you can get away with not worrying about it.
I need to load untrusted modules, written by third parties. I'm using vm for the sandbox and I was thinking to use threads (from npm: here) in order to load the module asynchronously and avoid blocking code.
I have stripped down the code to the minimum, because I'm stuck and I dont' understand if what I'm trying to achieve is impossible or it's just me messing with scopes.
Here is a dummy module:
exports.dummy = function () {
console.log('Dummy');
};
exports.val = 5;
And here is a module where I try to load this dummy module using threads:
var spawn = require('threads').spawn;
var mod;
var other;
var t = spawn(function (input, done) {
var m = require(input.dir + '/dummyMod');
done({m: m, other: 'hey'})
});
t.send({dir: __dirname}).on('message', function (result) {
mod = result.m;
other = result.other;
console.log(mod);
console.log(other);
t.kill();
});
The logged output is:
{ val: 5 }
hey
As you can see, the function in the dummy module has been skipped. If I try to load the module in the main process and log it, then the function is, of course, part of the object.
You need to properly serialize and deserialize the function. JSON.stringify ignores functions, probably because json is a format for storing data, not scripts.
Serialize the function by calling toString() on it. Then you can send it along as a string.
done({m: m.toString(), other: 'hey'})
Converting m to a string will give you something like this:
"function m(){console.log(\'called m()\')}"
On the receiving end, you will need to deserialize the function.
var m = new Function("return " + result.m)()
Inside a yeoman generator I am trying to do a conditional copy depending on the state of an external network resource. My problem is that the yeoman copy command (src.copy and template too for that matter) does not seem to do anything when invoked inside of an async callback, such as one from a http request.
Example code, inside of the yeoman.generators.NamedBase.extend block:
main: function(){
//-> here this.copy('inlocation','outlocation') works as expected
var that = this;
var appName = ...
var url = ...
var req = http.request(url, function(res){
//-> here that.copy('inlocation','outlocation') DOES NOT work
res.on('data', function (data) {
//console.log('Response received, onData event');
//-> here that.copy('inlocation','outlocation') DOES NOT work
});
//-> here that.copy('inlocation','outlocation') DOES NOT work
});
req.on('error',function(error){
//...
});
req.end();
//-> here this.copy('inlocation','outlocation') works as expected, once again
Note the locations marked by '//-->' comments for points of reference - when it works, it works as expected. When it doesn't, there's no output on console whatsoever (so that.copy seems to exist as a function, in fact I can assert that typeof that.copy === 'function' !), no error messages, just no file created (the usual file create message is missing too which is a characteristic of the properly working command).
Using call or apply to pass an explicit this reference to the functions didnt change the behaviour, nor did binding this to the async functions.
What is the explanation to this behaviour, and how can I make copy calls in this async manner?
As per Eric MORAND's comment, I'll post the solution I found as a separate answer, instead of an edit to the original post, hopefully it'll be easier to find:
I've found a solution, using the async() function of the yeoman RunContext. (see the api docs here) The following line at the beginning of the async code:
var done = this.async();
then a call to done() right before I wanted to run copy made it behave as originally expected.
I need to provide with error logging in my Windows 8 Metro application developed in Html/WinJS
so that user can get to know what went wrong from a log file located in the app's local folder.
I have checked WinJS.log(message, tags, type); which will write to the console but not able to find anything via which i can get it on a local file.
What is the best way to do the same and if there are any 3rd party libraries/js available for error logging in metro applications developed in WinJS ?
Thanks in advance.
WinJS.log is just a placeholder. Without proper initialization it does nothing (in fact, it's not set at all). If you just call WinJS.Utilities.startLog() at your application startup, it defaults to wiring up a logger for the console.
If you want something more complete, you'll need to build it. I've built a small sample below.
function startFileLog() {
// choose where the file will be stored:
var fileDestination = Windows.Storage.ApplicationData.current.localFolder;
var logger = new WinJS.Promise(function (complete) {
var logfilename = new Date().toISOString().replace(/[:-]/g, "");
logfilename = "log-" + logfilename + ".log";
fileDestination.createFileAsync(logfilename,
Windows.Storage.CreationCollisionOption.generateUniqueName)
.done(function (file) {
complete(file);
});
});
var actionFn = function (message, tag, type) {
logger.then(function (file) {
var m = WinJS.Utilities.formatLog(message, tag, type);
Windows.Storage.FileIO.appendTextAsync(file, m).done();
});
};
WinJS.Utilities.startLog({ action: actionFn });
}
By calling the startFileLog function above, it creates a new log file (by using the current Date/time as part of the file name) within a promise. Then, a function called actionFn is passed to the startLog function. By passing an optional property of the options named action, the default "write to console" behavior is overwritten (if you didn't want it overwritten, you could call startLog without the action, then copy the function reference from WinJS.log and replace it with your own function, and call it as well). When the log function is called, it now calls actionFn which uses the promise created earlier to verify that the log file is in fact available for writing before continuing. If it's not ready yet, it will be queued. So, this means that even though the file may not be ready immediately, the log will, in the end, contain the results you'd expect. There would be a short period of time where, due to async nature of WinJS, if the application crashed before the file completely opened, that logged items will be missed. You could delay the application startup if you wanted until the file was opened by returning the logger promise:
function startFileLog() {
/// ... etc..
return logger;
}
startFileLog().then(function() {
// the application can now be assured that the log file is ready to accept
// writes ... (but again, it's all async, so a write may be missed in
// extreme cases)
});
You'd likely want to create a function at the end of your application to clean/close the log file.
I recently refactored my javascript/jquery application code to use the module pattern.
I have two modules, lets say A and B.
Module B contains a public method(say, Bmethod) that makes a jQuery AJAX JSONP call($.ajax) and passes the response in a callback.
Inside Module A there is a call to B.Bmethod() with a callback function to handle the returned response.
Here is module B's definition:
var B = (function()
{
var obj = {};
obj.Bmethod = function(data, callback)
{
//do JSONP AJAX call
callback(response);
}
return obj;
}());
Now, here's module A's definition with the method call on module B
var A = (function()
{
var doAjax = function(data)
{
B.Bmethod(data, function(response)
{
//Do something with the response
});
}
}());
Here's how I load the module A and start the code execution:
$(document).ready(function()
{
A.doAjax(data);
});
The problem here is that, I have different behavior on Chrome and Firefox. On Chrome, the AJAX call is not being executed at all. There is no request sent. However, on Firefox, I can see the request made and also get a response back, but I do not receive a success callback.
If I put all of this code outside of modules, in just one single file, everything seems to work properly.
I have seen a lot of people(on StackOverflow as well) using the module pattern with AJAX calls successfully, but have not been able to figure out what I am doing wrong.
Any ideas/solutions?
Fixed the problem.
I was actually having a duplicate copy of the same AJAX request($.ajax) in a different file. So, when the request was being made, I am assuming the duplicate was (also)being called, and maybe this was causing inconsistency issues. However, on Chrome, setting a breakpoint showed no signs of the duplicate being called.
For now, I removed the duplicate request and it works fine. But, I still don't understand why there was an inconsistent behavior between Chrome and Firefox.